@inproceedings{oai:jaxa.repo.nii.ac.jp:00005039,
 author = {北本, 俊二 and 長崎, 健太 and 岸下, 徹一 and Kitamoto, Shunji and Watanabe, Aya and Nagasaki, Kenta and Kishishita, Tetsuichi},
 book = {宇宙航空研究開発機構特別資料:, JAXA Special Publication: The Energetic Cosmos; from Suzaku to ASTRO-H},
 month = {Feb},
 note = {The 3rd Suzaku international Conference "Energetic Cosmos : from Suzaku to ASTRO-H" (June 29-July 2, 2009. Grand Park Otaru Hotel), Otaru, Hokkaido Japan, We investigate an orbital X-ray modulation of the enigmatic X-ray binary, Cygnus X-3. It is a close binary system, composed of a Wolf-Rayet (WR) star and a compact star with a 4.8h orbital period. We determine a new precise orbital ephemeris and found that the orbital period is monotonically increasing with  (1/2)P(dP/dt) = (5.62 +/- 0.09) x 10(sup -11) day, over more than three decades from 1970s. The obtained period derivative is explained by an intense stellar wind from the WR star with approximately 10(sup from -6 to -5) solar mass yr(sup -1). This mass loss rate is a reasonable value as a Wolf-Rayet star. This thick wind exposed to intense X-rays should be photo-ionized. Observed rich emission lines come from this photo-ionized plasma as well as some narrow radiative recombination continuums (RRCs). We investigate an orbital modulation of the emissions lines and the RRCs. We found that the emission lines show a large equivalent width around phase 0.0 (phase 0.0 means the X-ray intensity minimum phase). However, the RRCs show different modulation pattern from that of the emission lines., Meeting sponsors: The University of Tokyo, The Institute of Physical and Chemical Research, The Japan Society for the Promotion of Science, 資料番号: AA0064574107, レポート番号: JAXA-SP-09-008E},
 pages = {288--289},
 publisher = {宇宙航空研究開発機構, Japan Aerospace Exploration Agency (JAXA)},
 title = {Orbital Modulation and a New Ephemeris of Cygnus X-3},
 volume = {JAXA-SP-09-008E},
 year = {2010}
}